Data storage medium and method for the preparation thereof

ABSTRACT

A data storage medium includes a substrate, a reflective metal layer, and a haze-prevention layer between the substrate and the reflective metal layer. The substrate includes an amorphous thermoplastic resin having a heat distortion temperature of at least about 140° C., a density less than 1.7 grams per milliliter, and an organic volatiles content less than 1,000 parts per million measured according to ASTM D4526. The haze-prevention layer includes a material having a volume resistivity of at least 1×10 −4  ohm-centimeters and a tensile modulus of at least about 3×10 5  pounds per square inch. The data storage medium resists hazing of the reflective layer at elevated temperatures.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 60/405,609, filed Aug. 23, 2002.

BACKGROUND

Reflective articles comprising a thermoplastic substrate and areflective metal layer are currently employed in a variety of productapplications, including automotive headlight reflectors and data storagemedia (e.g., data storage discs). Such articles may perform well atambient temperatures, but at the elevated temperatures encountered incertain manufacturing and use conditions, their reflectivity may beimpaired by the formation of haze in the reflective coating.

There is therefore a need for reflective articles that maintain theirreflectivity at elevated temperatures.

BRIEF SUMMARY

One embodiment is a data storage medium improved heat-resistance,comprising: a substrate comprising an amorphous thermoplastic resinhaving a heat distortion temperature of at least about 140° C. measuredat 66 pounds per square inch (psi) according to ASTM D648, a densityless than 1.7 grams per milliliter, and an organic volatiles contentless than 1,000 parts per million measured according to ASTM D4526; areflective metal layer; and a haze-prevention layer interposed betweenthe substrate and the reflective metal layer, wherein thehaze-prevention layer comprises a material having a volume resistivityof at least 1×10⁻⁴ ohm-centimeters measured according to ASTM D257 at25° C. and a tensile modulus of at least about 3×10⁵ pounds per squareinch measured according to ASTM D638 at 25° C.

Other embodiments, including a method of preparing the data storagemedium, are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a reflective article 10 comprising athermoplastic substrate 20, a reflective metal layer 30, and ahaze-prevention layer 40.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment is a data storage medium, comprising: a substratecomprising an amorphous thermoplastic resin having a heat distortiontemperature of at least about 140° C. measured at 66 psi according toASTM D648, a density less than 1.7 grams per milliliter, and an organicvolatiles content less than 1,000 parts per million measured accordingto ASTM D4526; a reflective metal layer; and a haze-prevention layerinterposed between the substrate and the reflective metal layer, whereinthe haze-prevention layer comprises a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch measured according to ASTM D638 at 25° C.

During the commercial development of reflectors for automotiveheadlights, it was sometimes observed that reflectors prepared by directmetalization of a thermoplastic substrate would initially exhibitexcellent reflectivity, but under conditions of use, hazing of thereflective surface would occur, leading to failure of the part. Throughextensive research on a variety of materials, the present inventors havediscovered that haze-formation under high-temperature conditions can bereduced or eliminated by interposing between the thermoplastic substrateand the reflective metal layer a haze-prevention layer comprising amaterial having a volume resistivity of at least 1×10⁻⁴ ohm-centimetersmeasured according to ASTM D257 at 25° C. and a tensile modulus of atleast about 3×10⁵ pounds per square inch measured according to ASTM D638at 25° C.

The substrate comprises an amorphous thermoplastic resin having a heatdistortion temperature of at least about 140° C., preferably at leastabout 170° C., more preferably at least about 185° C., still morepreferably at least about 200° C., measured at 66 psi according to ASTMD648. The amorphous thermoplastic also has a density less than 1.7grams/milliliter (g/mL), preferably less than 1.6 g/mL, more preferablyless than 1.5 g/mL. The density of the amorphous thermoplastic resin maybe determined at 25° C. according to ASTM D792. The amorphousthermoplastic resin is thus less dense than bulk molding compounds thathave often been used to form reflective articles. When the reflectivearticle is a headlight reflector, the use of the amorphous resin reducesthe weight of the headlight thereby contributes to weight reductionsthat allow more vehicle miles per gallon of fuel. The amorphousthermoplastic further has an organic volatiles content less than 1,000parts per million by weight, preferably less than 750 parts per millionby weight, more preferably less than 500 parts per million by weight,measured according to ASTM D4526. As specified in ASTM D4526, thevolatiles are determined by sampling a headspace in equilibrium with thethermoplastic at 90° C., and they are quantified using flame ionizationdetection. The organic volatiles content is thus lower than that of bulkmolding compounds, which may contain high concentrations of residualmonomers that outgas at elevated temperatures and decrease thereflectivity of the reflective metal layer. Suitable thermoplasticresins include, for example, polyetherimides, polyetherimide sulfones,polysulfones, polyethersulfones, polyphenylene ether sulfones,poly(arylene ether)s, polycarbonates, polyester carbonates,polyarylates, and the like, and mixtures thereof. These thermoplasticsand methods for their preparation are known in the art.

Preferred polyetherimides include those comprising structural units ofthe formula (I)

wherein the divalent T moiety bridges the 3,3′, 3,4′, 4,3′, or 4,4′positions of the aryl rings of the respective aryl imide moieties offormula (I); T is —O— or a group of the formula —O—Z—O—; Z is a divalentradical selected from the group consisting of formulae (II)

wherein X is a member selected from the group consisting of divalentradicals of the formulae (III)

wherein y is an integer of 1 to about 5, and q is 0 or 1; R is adivalent organic radical selected from (a) aromatic hydrocarbon radicalshaving 6 to about 20 carbon atoms and halogenated derivatives thereof,(b) alkylene radicals having 2 to about 20 carbon atoms, (c)cycloalkylene radicals having 3 to about 20 carbon atoms, and (d)divalent radicals of the general formula (IV)

where Q is a covalent bond or a member selected from the groupconsisting of formulae (V)

where y′ is an integer from 1 to about 5.

In the formulas above, when X or Q comprises a divalent sulfone linkage,the polyetherimide may be considered a polyetherimide sulfone.

Generally, useful polyetherimides have a melt index of about 0.1 toabout 10 grams per minute (g/min), as measured by American Society forTesting Materials (ASTM) D1238 at 337° C., using a 6.6 kilogram weight.

In a preferred embodiment, the polyetherimide resin has a weight averagemolecular weight of about 10,000 to about 150,000 atomic mass units(AMU), as measured by gel permeation chromatography using polystyrenestandards. Such polyetherimide resins typically have an intrinsicviscosity greater than about 0.2 deciliters per gram measured inm-cresol at 25° C. An intrinsic viscosity of at least about 0.35deciliters per gram may be preferred. Also, an intrinsic viscosity of upto about 0.7 deciliters per gram may be preferred.

Included among the many methods of making the polyetherimide resin arethose described, for example, in U.S. Pat. No. 3,847,867 to Heath etal., U.S. Pat. No. 3,850,885 to Takekoshi et al., U.S. Pat. Nos.3,852,242 and 3,855,178 to White, and U.S. Pat. No. 3,983,093 toWilliams et al.

In a preferred embodiment, the polyetherimide resin comprises structuralunits according to formula (I) wherein each R is independentlyparaphenylene or metaphenylene and T is a divalent radical of theformula (VI).

A particularly preferred polyetherimide resin is the reaction productformed by melt polymerization of2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with one ormore of paraphenylene diamine and metaphenylene diamine. Thepolyetherimides are commercially available from General Electric Companyas ULTEM® resins, including, for example, ULTEM® 1000, ULTEM® 1010,ULTEM® 6000, ULTEM® XH6050, and ULTEM® CRS5000. Additional descriptionof polyetherimide polymers may be found, for example, in ASTM 5205,Standard Classification System for Polyetherimide (PEI) Materials.

Polysulfones suitable for use in the thermoplastic substrate arepolymeric comprising repeating units having at least one sulfone group.Polysulfones and methods for their preparation are well known in the artand described, for example, in U.S. Pat. No. 3,642,946 to Grabowski etal.; and Kirk-Othmer, Encyclopedia of Chemical Technology, SecondEdition, Vol. 16, pp. 272-281 (1968). Representative polymers of thistype include polysulfones, polyether sulfones, and polyphenyl sulfones.

The polysulfones that may be utilized in the instant invention containat least one recurring structural unit represented by the generalformula (VII)

wherein each occurrence of Ar is independently unsubstituted phenyleneor phenylene substituted with phenyl, C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy,halogen, nitro, or the like; and each occurrence of A is independently adirect carbon-to-carbon bond, C₁-C₁₂ alkylidene, C₃-C₈ cycloalkylidene,carbonyl sulfoxide, sulfur, sulfone, azo, imino, oxygen, or the like.

The polysulfones of Formula (VII) are preferably derived fromdichlorodiphenyl sulfones reacted with bisphenols. A second group ofsulfones represented by Formula I is one in which each Ar is phenyleneand A is sulfone. A third major group of polysulfones represented byFormula I are those wherein each Ar is phenylene and A is oxygen, i.e.,the polyarylethersulfones. When Ar is phenylene, it should preferably beeither meta or para and may be substituted in the ring positions withC₁-C₆ alkyl groups, C₁-C₆ alkoxy groups, or the like. Particularlyuseful polysulfones are those derived from disulfonyl chlorides such as4,4-biphenyldisulfonyl chloride reacted with 4,4′-dihydroxydiphenylether.

The polyarylethersulfones, including polyphenylene ether sulfones,contain at least the following recurring structural units

wherein R, R¹ and R² are independently selected from C₁-C₆ alkyl, C₄-C₈cycloalkyl, and halogen radicals; W is a C₂-C₈ alkylene, a C₁-C₈alkylidene, a cycloalkylene or cycloalkylidene radical containing from 4to about 16 ring carbon atoms, or the like; b is 0 or 1; and n, n1, andn2 are independently 0, 1, 2, 3, or 4. Additional description ofpolysulfone may be found, for example, in ASTM D6394, StandardSpecification for Sulfone Plastics (SP).

Suitable poly(arylene ether)s include polyphenylene ether (PPE) andpoly(arylene ether) copolymers; graft copolymers; poly(arylene ether)ether ionomers; and block copolymers of alkenyl aromatic compounds,vinyl aromatic compounds, and poly(arylene ether), and the like; andcombinations comprising at least one of the foregoing; and the like.Poly(arylene ether)s are known polymers comprising a plurality ofstructural units of the formula

wherein for each structural unit, each Q¹ is independently halogen,primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ² is independently hydrogen, halogen, primary or secondary C₁-C₈ alkyl,phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, orC₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate thehalogen and oxygen atoms. Preferably, each Q¹ is alkyl or phenyl,especially C₁₋C₄ alkyl, and each Q² is independently hydrogen or methyl.

Both homopolymer and copolymer poly(arylene ether)s are included. Thepreferred homopolymers are those comprising 2,6-dimethylphenylene etherunits. Suitable copolymers include random copolymers comprising, forexample, such units in combination with 2,3,6-trimethyl-1,4-phenyleneether units or copolymers derived from copolymerization of2,6-dimethylphenol with 2,3,6-trimethylphenol. Such copolymers of2,6-dimethylphenol and 2,3,6-trimethylphenol, especially thosecontaining about 5 to about 50 weight percent of units derived from2,3,6-trimethylphenol, are particularly preferred for their heatresistance. Also included are poly(arylene ether)s containing moietiesprepared by grafting vinyl monomers or polymers such as polystyrenes, aswell as coupled poly(arylene ether) in which coupling agents such as lowmolecular weight polycarbonates, quinones, heterocycles and formalsundergo reaction in known manner with the hydroxy groups of twopoly(arylene ether) chains to produce a higher molecular weight polymer.Poly(arylene ether)s of the present invention further includecombinations of any of the above, including blends of poly(aryleneether)s and polystyrene resins.

The poly(arylene ether) generally has a number average molecular weightof about 3,000 to about 40,000 atomic mass units (AMU) and a weightaverage molecular weight of about 20,000 to about 80,000 AMU, asdetermined by gel permeation chromatography. The poly(arylene ether)generally may have an intrinsic viscosity of about 0.2 to about 0.6deciliters per gram (dL/g) as measured in chloroform at 25° C. Withinthis range, the intrinsic viscosity may preferably be up to about 0.5dL/g, more preferably up to about 0.47 dL/g. Also within this range, theintrinsic viscosity may preferably be at least about 0.3 dL/g. It isalso possible to utilize a high intrinsic viscosity poly(arylene ether)and a low intrinsic viscosity poly(arylene ether) in combination.Determining an exact ratio, when two intrinsic viscosities are used,will depend on the exact intrinsic viscosities of the poly(aryleneether)s used and the ultimate physical properties desired.

The poly(arylene ether)s are typically prepared by the oxidativecoupling of at least one monohydroxyaromatic compound such as2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generallyemployed for such coupling. They typically contain at least one heavymetal compound such as a copper, manganese or cobalt compound, usuallyin combination with various other materials. Suitable methods forpreparing poly(arylene ether)s are described, for example, in U.S. Pat.Nos. 3,306,874 and 3,306,875 to Hay, and U.S. Pat. Nos. 4,011,200 and4,038,343 to Yonemitsu et al.

Suitable polycarbonates may be prepared by reacting a dihydric phenolwith a carbonate precursor, such as phosgene, a haloformate, or acarbonate ester. Generally, such carbonate polymers possess recurringstructural units of the formula

wherein A is a divalent aromatic radical of the dihydric phenol employedin the polymer producing reaction. Preferably, the carbonate polymersused to provide the resinous mixtures of the invention have an intrinsicviscosity (as measured in methylene chloride at 25° C.) of about 0.30 toabout 1.00 dL/g. The dihydric phenols employed to provide such aromaticcarbonate polymers may be mononuclear or polynuclear aromatic compounds,containing as functional groups two hydroxy radicals, each of which isattached directly to a carbon atom of an aromatic nucleus. Typicaldihydric phenols include, for example, 2,2-bis(4-hydroxyphenyl)propane(bisphenol A); hydroquinone; resorcinol;2,2-bis(4-hydroxyphenyl)pentane; 2,4′-(dihydroxydiphenyl)methane;bis(2-hydroxyphenyl)methane; bis(4-hydroxyphenyl)methane;bis(4-hydroxy-5-nitrophenyl)methane; 1,1 -bis(4-hydroxyphenyl)ethane;3,3-bis(4-hydroxyphenyl)pentane; 2,2-dihydroxydiphenyl;2,6-dihydroxynaphthalene; bis(4-hydroxydiphenyl)sulfone;bis(3,5-diethyl-4-hydroxyphenyl)sulfone;2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; 2,4′-dihydroxydiphenylsulfone; 5′-chloro-2,4′-dihydroxydiphenyl sulfone;bis(4-hydroxyphenyl)diphenyl sulfone; 4,4′-dihydroxydiphenyl ether;4,4′-dihydroxy-3,3′-dichlorodiphenyl ether;4,4-dihydroxy-2,5-dihydroxydiphenyl ether; and the like.

Other dihydric phenols suitable for use in the preparation ofpolycarbonate resins are described, for example, in U.S. Pat. No.2,999,835 to Goldberg, U.S. Pat. No. 3,334,154 to Kim, and U.S. Pat. No.4,131,575 to Adelmann et al.

These aromatic polycarbonates can be manufactured by known processes,such as, for example and as mentioned above, by reacting a dihydricphenol with a carbonate precursor, such as phosgene, in accordance withmethods set forth in the above-cited literature and in U.S. Pat. No.4,123,436 to Holub et al., or by transesterification processes such asare disclosed in U.S. Pat. No. 3,153,008 to Fox, as well as otherprocesses known to those skilled in the art.

It is also possible to employ two or more different dihydric phenols ora copolymer of a dihydric phenol with a glycol or with a hydroxy- oracid-terminated polyester or with a dibasic acid in the event acarbonate copolymer or interpolymer rather than a homopolymer isdesired. Branched polycarbonates are also useful, such as are describedin U.S. Pat. No. 4,001,184 to Scott. Also, there can be utilized blendsof linear polycarbonate and a branched polycarbonate. Moreover, blendsof any of the above materials may be employed in the practice of thisinvention to provide the aromatic polycarbonate.

These polycarbonates may be branched or linear and generally will have aweight average molecular weight of about 10,000 to about 200,000 AMU,preferably from about 20,000 to about 100,000 as measured by gelpermeation chromatography. The polycarbonates of the invention canemploy a variety of end groups to improve performance. Bulky monophenols, such as cumyl phenol, are preferred.

Suitable polycarbonates further include those derived from bisphenolscontaining alkyl cyclohexane units. Such polycarbonates have structuralunits corresponding to the structure

wherein R^(a)-R^(d) are each independently hydrogen, C₁-C₁₂ hydrocarbyl,or halogen; and R^(e)-R^(i) are each independently hydrogen, C₁-C₁₂hydrocarbyl. As used herein, “hydrocarbyl” refers to a residue thatcontains only carbon and hydrogen. The residue may be aliphatic oraromatic, straight-chain, cyclic, bicyclic, branched, saturated, orunsaturated. The hydrocarbyl residue, when so stated however, maycontain heteroatoms over and above the carbon and hydrogen members ofthe substituent residue. Thus, when specifically noted as containingsuch heteroatoms, the hydrocarbyl residue may also contain carbonylgroups, amino groups, hydroxyl groups, or the like, or it may containheteroatoms within the backbone of the hydrocarbyl residue. Alkylcyclohexane containing bisphenols, for example the reaction product oftwo moles of a phenol with one mole of a hydrogenated isophorone, areuseful for making polycarbonate resins with high glass transitiontemperatures and high heat distortion temperatures. Such isophoronebisphenol-containing polycarbonates have structural units correspondingto the structure

wherein R^(a)-R^(d) are as defined above. These isophorone bisphenolbased resins, including polycarbonate copolymers made containingnon-alkyl cyclohexane bisphenols and blends of alkyl cyclohexylbisphenol containing polycarbonates with non-alkyl cyclohexyl bisphenolpolycarbonates, are supplied by Bayer Co. under the APEC trade name anddescribed, for example, in U.S. Pat. No. 5,034,458 to Serini et al.

Suitable thermoplastic resins further include “polyarylates,” which isthe common term referring to polyesters of aromatic dicarboxylic acidsand bisphenols. Polyarylate copolymers including carbonate linkages inaddition to the aryl ester linkages, known as polyester-carbonates, arealso suitable. These resins may be used alone or in combination witheach other or more preferably in combination with bisphenolpolycarbonates. These resins can be prepared in solution or by meltpolymerization from aromatic dicarboxylic acids or their ester formingderivatives and bisphenols and their derivatives. Suitable dicarboxylicacids are iso- and terephthalic acid, their esters or acid chlorides. Apreferred bisphenol is bisphenol A or its diacetate derivative.Polyester carbonates and polyarylates may also contain linkages derivedfrom hydroxy carboxylic acids such as hydroxy benzoic acid. The mostpreferred polyester-carbonates and polyarylates are amorphous resinsderived from bisphenol A and mixtures of isophthalic and terephthalicacid. Suitable polyarylates and their preparation are described, forexample, in U.S. Pat. No. 4,663,421 to Mark. Suitablepolyester-carbonates and their preparation are described, for example,in U.S. Pat. No. 3,169,121 to Goldberg, and U.S. Pat. No. 4,156,069 toPrevorsek et al.

In one embodiment, the substrate comprises at least about 50% by weight,preferably at least about 80% by weight, more preferably at least about90% by weight, still more preferably at least about 95% by weight, ofthe thermoplastic resin.

In one embodiment the substrate comprises, in addition to thethermoplastic resin, an inorganic filler such as, for example, talc,mica, clay, titanium dioxide, zinc oxide, zinc sulfide, wollastonite, orthe like, or a mixture thereof.

In another embodiment, the substrate is substantially free of inorganicfiller. “Substantially free of inorganic filler” is defined herein ascomprising less than 0.1 weight percent of inorganic filler. It may bepreferred that the substrate comprises less than 0.01 weight percent ofinorganic filler.

The substrate resin may further contain additives to improve meltprocessing, molding or part stability. Useful additives includelubricants and mold release agents, such as aliphatic esters, forexample pentaerythritol tetrastearate, or polyolefins, for example highdensity polyethylene. Stabilizers, such as aryl phosphite and hinderedphenols may also be blended with the substrate resin. Other additivesinclude compounds to reduce static charge build up. If employed in thesubstrate, it is important to select such additives so that they arethermally stable, show low volatility and do not contribute to hazing inthe metallized article.

The dimensions of the substrate will be dictated by the use of thereflective article. For example, when the reflective article is aheadlight reflector, it may have a thickness of about 0.1 to about 20millimeters in the dimension perpendicular to the haze-prevention layerand the reflective metal layer; within this range, the thickness maypreferably be at least about 0.5 millimeters, more preferably at leastabout 1 millimeter; also within this range, the thickness may preferablybe up to about 10 millimeters, more preferably up to about 8millimeters. As another example, when the reflective article is a datastorage disc, it may have a thickness of about 0.1 to about 5millimeters in the dimension perpendicular to the haze-prevention layerand the reflective metal layer; within this range, the thickness maypreferably be at least about 0.5 millimeters, more preferably at leastabout 1 millimeter; also within this range, the thickness may preferablybe up to about 4 millimeters, more preferably up to about 3 millimeters.

The reflective article comprises a reflective metal layer. Metalssuitable for use in the reflective metal layer include the metals ofGroups IIIA, IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB of the periodictable. Mixtures and alloys of these metals may also be used. Preferredmetals include aluminum, silver, gold, nickel, palladium, platinum,copper, and the like, and alloys comprising at least one of theforegoing metals. Aluminum and its alloys are particularly preferredmetals for the reflective metal layer.

The reflective metal layer may be formed using methods known in the art,including sputtering, vacuum metal deposition, vapor arc deposition,plasma chemical vapor deposition, thermal vapor metal deposition, andion plating.

The reflective metal layer may have a thickness of about 1 to about 1000nanometers. Within this range, the thickness may preferably be at leastabout 10 nanometers, more preferably at least about 20 nanometers. Alsowithin this range, the thickness may preferably be up to about 500nanometers, more preferably up to about 200 nanometers.

The reflective article comprises a haze-prevention layer interposedbetween the substrate and the reflective metal layer. Thehaze-prevention layer comprises comprising a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch (2068 megapascals) measured according to ASTM D638 at25° C. The volume resistivity may preferably be at least 1×10⁻²ohm-centimeters, more preferably at least 1 ohm-centimeter. The tensilemodulus may preferably be at least about 5×10⁵ pounds per square inch(3447 megapascals), more preferably at least about 8×10⁵ pounds persquare inch (5516 megapascals), still more preferably at least about1×10⁶ pounds per square inch (6895 megapascals). In a preferredembodiment, the haze prevention layer has a tensile modulus of at least3×10⁵ pounds per square inch (2068 megapascals) measured at the heatdistortion temperature of the amorphous resin employed in the substrate.In this embodiment, if the substrate includes more than one amorphousresin, the tensile modulus is measured at the lowest heat distortiontemperature of any amorphous resin. The haze-prevention layer ispreferably non-metallic, and plasma-polymerized haze-prevention layersare highly preferred. In addition to meeting the above resistivitylimitation, the non-metallic haze-prevention layer may preferablycomprise less than 1 weight percent total of zero-valent metals.

In one embodiment, the haze-prevention layer comprises aplasma-polymerized organosilicone. A plasma-polymerized organosilicone,sometimes called a hydroxy silicon carbide or silicon oxy carboncoating, is a product of plasma deposition of a silicone precursorhaving the formula

wherein each R is independently hydrogen, C₁-C₆ alkyl, C₂-C₆ alkenyl,C₃-C₆ alkenyl alkyl, C₆-C₁₈ aryl, or the like; n is 0 to about 100; m is1 to about 100; and X is —O— or —NH—.

Preferred organosilicone compounds include

and the like, and mixtures thereof.

Plasma polymerization of the organosilicone may take place in thepresence of a small amount of oxygen that may be incorporated into thecoating. The plasma-polymerized organosilicone haze-reduction layer canbe formed from a variety of plasma deposition techniques includingplasma assisted or enhanced chemical vapor deposition (PECVD, PACVD)using plasma sources of radio frequency (RF), microwave (MW),inductively coupled plasma (ICP), electron cyclotron resonance (ECR),hollow cathode, thermal plasma, expanding thermal plasma (ETP), andplasma arcs or jets. In a preferred embodiment, the haze reduction layeris deposited by ETP as described in patents U.S. Pat. No. 6,420,032 toIacovangelo and U.S. Pat. No. 6,397,776 to Yang et al.

In one embodiment, the haze-prevention layer comprises at least about 50weight percent, preferably at least about 80 weight percent, morepreferably at least about 90 weight percent, still more preferably atleast about 95 weight percent of the plasma-polymerized organosilicone,based on the total weight of the haze-prevention layer.

In another embodiment, the haze-prevention layer comprises diamond-likecarbon. A haze-prevention layer comprising diamond-like carbon may beformed from plasma-assisted chemical vapor deposition of organic monomeras described, for example, in U.S. Pat. No. 5,506,038 to Knapp et al.,and U.S. Pat. Nos. 5,527,596 and 5,508,092 to Kimock et al.

In another embodiment, the haze-prevention layer comprises a colloidalsilica composition comprising colloidal silica dispersed in a silanol-,acrylic-, or methacrylic-derived polymer system. For example, thecolloidal silica composition may be an acidic dispersion of colloidalsilica and hydroxylated silsesquioxane in an alcohol-water medium. Moreparticularly, the coating composition may be a dispersion of colloidalsilica in a lower aliphatic alcohol-water solution of a silanol havingthe formula RSi(OH)₃ in which R may be, for example, C₁-C₃ alkyl, vinyl,3,3,3-trifluoropropyl, gamma-glycidoxypropyl, gamma-methacryloxypropyl,or the like. Preferably, at least 70 percent of the silanol isCH₃Si(OH)₃. The composition may comprise, for example, 10 to 50 weightpercent solids consisting essentially of 10 to 70 weight percentcolloidal silica and 30 to 90 weight percent of a partial condensate ofthe silanol (i.e., a hydroxylated silsesquioxane), the compositioncontaining sufficient acid to provide a pH in the range of 3.0 to 6.0.Suitable coating compositions and their preparation are described, forexample, in U.S. Pat. No. 3,986,997 to Clark and U.S. Pat. No. 5,346,767to Tilley et al.

As another example, the colloidal silica composition may be a silicacontaining coating composition comprising about 10 to 50 weight percentsolids dispersed in a water/aliphatic alcohol mixture wherein the solidscomprise about 10 to 70 weight percent ammonium hydroxide-stabilizedcolloidal silica and about 30 to 90 weight percent of a partialcondensate derived from an organotrialkoxy silane of the formulaR′Si(OR)₃ wherein R′ may be, for example, C₁-C₃ alkyl, C₆-C₁₃ aryl, orthe like, and R may be, for example, C₁-C₈ alkyl, C₆-C₂₀ aryl, or thelike, the composition having a pH of from about 7.1 to about 7.8.Suitable coating compositions and their preparation are described, forexample, in U.S. Pat. No. 4,624,870 to Blair and U.S. Pat. No. 5,346,767to Tilley et al.

As a third example, the colloidal silica composition may be anultraviolet light curable coating comprising about 1 to about 60 weightpercent colloidal silica; about 1 to about 50 weight percent of thematerial produced by the hydrolysis of silyl acrylate; and about 25 toabout 90 weight percent of an acrylate monomer. The composition may,optionally, further include about 0.1 to about 5 weight percent of a UVphotoinitiator. Preferred compositions are derived from aqueouscolloidal silica, 2-methacryloxy-propyltrimethoxysilane,hexanediolacrylate, and a photosensitizing amount of a photoinitiator.Suitable compositions and their preparation are described, for example,in U.S. Pat. No. 4,491,508 to Olson et al. and U.S. Pat. No. 5,346,767to Tilley et al.

As a fourth example, the colloidal silica composition may be anultraviolet light curable coating comprising 100 parts by weight ofcolloidal silica; 5-500 parts by weight of an acryloxy-functional silaneor glycidoxy-functional silane; 10-500 parts by weight of a non-silylacrylate; and a catalytic amount of an ultraviolet light sensitivephotoinitiator. Preferred compositions comprise aqueous colloidalsilica, methacryloxypropyl trimethoxysilane, hexanedioldiacrylate, aglycidyloxy functional silane, and a cationic photoinitiator. Thesecompositions and their preparation are disclosed in U.S. Pat. No.4,348,462 to Chung, U.S. Pat. No. 4,491,508 to Olson, and U.S. Pat. No.5,346,767 to Tilley et al.

In one embodiment, the haze-prevention layer comprises at least about 50weight percent, preferably at least about 80 weight percent, morepreferably at least about 90 weight percent, still more preferably atleast about 95 weight percent of the colloidal silica composition, basedon the total weight of the haze-prevention layer.

In one embodiment, the haze-prevention layer comprises a thermosetresin. Suitable thermoset resins include thermoset polyester resins,thermoset epoxy resins, novolac resins, melamine resins, and the like.Such resins are well known in the art and commercially available.

In one embodiment, the haze-prevention comprises at least about 50weight percent, preferably at least about 80 weight percent, morepreferably at least about 90 weight percent, still more preferably atleast about 95 weight percent of the thermoset resin, based on the totalweight of the haze-prevention layer.

The thickness of the haze-prevention layer will depend on itscomposition, but it is generally about 10 nanometers to about 100micrometers. Within this range, the thickness may preferably be at leastabout 20 nanometers, more preferably at least about 40 nanometers. Alsowithin this range, the thickness may preferably be up to about 50micrometers, more preferably up to about 10 micrometers. Depending onthe material employed in the haze-prevention layer, it may be possibleto use thinner haze-prevention layers. For example, when thehaze-prevention layer comprises a plasma-polymerized organosilicone, thethickness may be less than 100 nanometers, preferably less than 90nanometers, more preferably less than 80 nanometers, still morepreferably less than 70 nanometers.

Although the substrate is well suited for direct application of ahaze-prevention layer, it is also possible to pre-coat the substratewith a primer before applying the haze-prevention layer. It may also beadvantageous to further coat the reflective article with a clear, hardprotective layer to protect the reflective metal layer from scratching,oxidation, or related problems. The protective layer may, preferably,exhibit a percent transmittance greater than 90 percent measurednanometers according to ASTM D1003. The protective layer may,preferably, exhibit a yellowness index less than 5 measured according toASTM D1925. Suitable compositions and methods for preparing protectivemetal oxide layers are described, for example, in U.S. Pat. No.6,110,544 to Yang et al., and U.S. Pat. No. 6,379,757 B1 to Iacovangelo.Thus, in one embodiment, the reflective article includes a substrate, ahaze-prevention layer, a reflective layer, and a protective layer,wherein the haze-prevention layer is interposed between substrate andthe reflective layer, and the reflective layer is interposed between thehaze-prevention layer and the protective layer.

In a preferred embodiment, the reflective article comprises a surfacehaving a reflectivity of at least 80%, more preferably at least about85%, even more preferably at least about 90%, measured according to ASTMD523. In a highly preferred embodiment, the reflective article comprisesa surface having a reflectivity of at least 80%, more preferably atleast about 85%, even more preferably at least about 90%, after 15minutes exposure to the lowest heat distortion temperature of anythermoplastic resin in the substrate.

FIG. 1 presents an exploded perspective view of a section of areflective article 10. Haze-prevention layer 40 is interposed betweensubstrate 20 and reflective metal layer 30.

The reflective article may be used, for example, as an automotiveheadlight reflector, a reflector incorporated into a projector lamp, amirror of any shape and curvature. Headlight reflectors and theirpreparation is described, for example, in U.S. Pat. No. 4,210,841 toVodicka et al., U.S. Pat. No. 5,503,934 to Maas et al., and U.S. Pat.No. 6,355,723 B1 to van Baal et al. Data storage media and methods fortheir preparation are described, for example, in U.S. Pat. No. 5,783,653to Okamoto et al., and U.S. Pat. No. 6,436,503 to Cradic et al., as wellas U.S. patent application Publication Nos. 2002-0048691 A1 to Davis etal., 2002-0094455 A1 to Feist et al., 2002-0197438 A1 to Hay et al., and2003-0044564 A1 to Dris et al.

In an embodiment preferred for its simplicity, the reflective articleconsists essentially of: a substrate comprising an amorphousthermoplastic resin having a heat distortion temperature of at leastabout 140° C. measured at 66 psi according to ASTM D648, a density lessthan 1.7 grams per milliliter, and an organic volatiles content lessthan 1,000 parts per million measured according to ASTM D4526; areflective metal layer; and a haze-prevention layer interposed betweenthe substrate and the reflective metal layer, wherein thehaze-prevention layer comprises a material having a volume resistivityof at least 1×10⁻⁴ohm-centimeters measured according to ASTM D257 at 25°C. and a tensile modulus of at least about 3×10⁵ pounds per square inchmeasured according to ASTM D638 at 25° C.

In a preferred embodiment, the reflective article is a data storagemedium that comprises: a substrate comprising a polysulfone or anisophorone bisphenol-containing polycarbonate resin having a glasstransition temperature of at least about 170° C., a density less than1.7 grams per milliliter, and an organic volatiles content less than1,000 parts per million measured according to ASTM D4526; a reflectivemetal layer comprising aluminum; and a plasma-polymerized organosiliconehaze-prevention layer interposed between the substrate and thereflective metal layer, wherein the haze-prevention layer comprises aplasma-polymerized organosilicone having a volume resistivity of atleast 1×10⁻² ohm-centimeters measured according to ASTM D257 at 25° C.and a tensile modulus of at least about 5×10⁵ pounds per square inchmeasured according to ASTM D638.

Another embodiment is a method for preparing a data storage medium,comprising: applying a haze-prevention layer to a surface of asubstrate, wherein the haze-prevention layer comprises a material havinga volume resistivity of at least 1×10⁻⁴ ohm-centimeters measuredaccording to ASTM D257 at 25° C. and a tensile modulus of at least about3×10⁵ pounds per square inch measured according to ASTM D638, andwherein the substrate comprises an amorphous thermoplastic resin havinga heat distortion temperature of at least about 140° C. measuredaccording to ASTM D648, a density less than 1.7 grams per milliliter,and an organic volatiles content less than 1,000 parts per millionmeasured according to ASTM D4526; and applying a reflective metal layerto a surface of the haze-prevention layer.

The invention is further illustrated by the following non-limitingexamples. Examples of the invention are designated by numbers.Comparative examples are designated by letters.

COMPARATIVE EXAMPLE A, EXAMPLES 1-3

Injection molded 102 millimeter diameter×3.2 millimeter thick discs ofpolyetherimide (ULTEM 1010 from GE Plastics Co.) were coated using thefollowing process: samples were pumped down in a vacuum chamber and glowcleaned at a power setting of 3.0 kW for 180 seconds at 0.023 torr. Theparts were the pre-coated with a haze-reducing plasma-polymerizedorganosilicone coating made by introducing hexamethyldisiloxane (HMDSO)into the chamber and creating a plasma. The pressure was 0.027 to 0.036torr, and the power was 3.2 kilowatts (kW). The plasma-polymerizedorganosilicone coating time was varied from 2 to 4 to 8 minutes to givea plasma-polymerized organosilicone coating thickness of about 40 toabout 145 nm. The parts were then coated with about 100 nm of aluminumat 0.00005 torr. A post metallization protective top-coat was thenapplied at 0.027 torr, power 3.2 kW for 180 seconds. Coated samples werethen subject to a post glow for 180 seconds at 3.2 kW at 0.018 torr andwere taken from the chamber.

In order to test the haze-prevention performance of the samples coatedwith plasma-polymerized organosilicone, the parts were heated from 198to 210° C. in 2° C. increments and observed for haze. Results are shownin Table 1. Comparative Example A, the metallized polyetherimide (PEI)control with no plasma-polymerized organosilicone haze-prevention layer,showed haze at 204° C. Example 1, with a two minute plasma-polymerizedorganosilicone haze-prevention layer, resisted haze formation until 208°C. Example 2, with a 4 minute plasma-polymerized organosiliconehaze-prevention layer, resisted haze up to 210° C. Example 3, with aneight minute plasma-polymerized organosilicone haze-prevention layer,showed a haze resistance up to 210° C.

TABLE 1 Plasma-Polymerized Organosilicone Coating Haze Onset ° C.Thickness Example A PEI-No plasma- 204 None polymerized organosiliconeunder-coat Example 1 PEI-2 minute 208  41 nm plasma-polymerized or-ganosilicone under- coat Example 2 PEI-4 minute 210  64 nmplasma-polymerized or- ganosilicone under-coat Example 3 PEI-8 minute210 145 nm plasma-polymerized or- ganosilicone under-coat

COMPARATIVE EXAMPLES B-I, EXAMPLES 4-11

Disks, 102 millimeter×3.2 millimeter, of various high glass transitiontemperature (T_(g)) thermoplastics resins (Table 2) were injectionmolded and metallized as described above. Control examples (B-I) werecoated with a reflective aluminum coating of about 100 nm that was thenprotected with a top-coat layer. Examples of the invention (4-11) werefirst coated for about four minutes with a haze reducing hydroxy siliconcarbide layer generated from the plasma deposition of HMDSO. The hydroxysilicon carbide layer thickness was about 64 nm. The samples were thencoated with a reflective layer of aluminum and top-coated with aprotective layer.

Table 2 shows the high Tg resins tested. Heat distortion temperature(HDT) was measured according to ASTM D648. Glass transition temperaturewas measured by differential scanning calorimetry (DSC) according toASTM D3418.

TABLE 2 HDT @ 66 psi Thermoplastic Resin T_(g) (° C.) (° C.)Polyethersulfone, ULTRASON E2010 220 208 from BASF Co. Bisphenol APolysulfone, UDEL P-1700 185 178 from Solvay Co. Bisphenol APolycarbonate, LEXAN 141 148 140 from GE Plastics Co. Isophoronebisphenol based polycarbon- 184 174 ate, APEC 9359 from Bayer Co.Isophorone bisphenol based polycarbon- 206 190 ate, APEC 9379 from BayerCo. 75:25 blend of Polyetherimide and Poly- 215 & 175 197 carbonateester, ULTEM ATX200 from GE Plastics Polyetherimide with mold release,217 207 ULTEM 1010M from GE Plastics Co. Polyetherimide Sulfone, ULTEMXH6050 249 237 from GE Plastics Co.

The coated samples were then heated in an air-circulating oven toexamine haze formation. The initial temperature was about 20° C. belowthe glass transition temperature of each different resin. Thetemperature was raised in 2° C. increments until hazing was observed.Samples were held for about 90 minutes at each temperature. For eachtype of resin the control sample and the haze reduced samples wereheated under the same conditions. Heating temperatures were varied toreflect the heat capability (T_(g) and HDT) of each individual resin orresin mixture.

Table 3 shows the temperature at which haze formation is first observedfor control samples B-I, in which substrates were coated with just areflective aluminum layer, and samples of the invention, 4-11, includinga substrate, a plasma-polymerized organosilicone haze-prevention layer,and a reflective metal layer. Note that for each resin theplasma-polymerized organosilicone underlayer (haze-prevention layer)imparts an increased resistance to hazing; the onset of hazing is seenat a higher temperature.

TABLE 3 Only Reflective layer reflective with plasma- layer In-polymerized Control Onset vention organosilicone Thermoplastic Ex- HazeEx- underlayer Resin ample (° C.) ample Onset Haze (° C.)Polyethersulfone B 206 4 216 Bisphenol A C 178 5 182 PolysulfoneBisphenol A D 139 6 143 Polycarbonate Isophorone bisphenol E 173 7 178based polycarbonate, APEC 9359 Isophorone bisphenol F 184 8 194 basedpolycarbonate, APEC 9379 75:25 blend of G 196 9 198 Polyetherimide andPolyester carbonate Polyetherimide with H 204 10 210 mold releasePolyetherimide I 221 11 225 Sulfone

COMPARATIVE EXAMPLES J AND K

Two polycarbonate plaques (LEXAN® 140, obtained from General ElectricCompany) having thicknesses of 1.52 and 6.35 millimeters were metallizedwith aluminum by DC magnetron sputtering at 70 watts and 8 millitorr for20 minutes to produce a reflective layer thickness of about 100-200nanometers. The metallized samples were placed in an air-circulatingoven for various lengths of time at increasing temperatures. At an oventemperature of 125° C., samples did not haze after 48 hours, but at 138°C., samples became hazy after about 10 to 20 minutes. Haze was observedvisually. Selected samples were also examined by optical microscopy.

EXAMPLES 12 AND 13

The procedure of Comparative Examples J and K was followed, except thatthe polycarbonate plaques were pre-coated with an acrylic-modifiedcolloidal silica composition before metalization. The acrylic-modifiedcolloidal silica composition was obtained as an AS4000 suspension fromGE Silicones and applied by flow coating and thermal curing to produce acured haze reducing layer coating thickness of about 6-8 micrometers.After metallization with aluminum, samples showed no evidence of hazeafter up to 24 hours at temperatures as high as 145° C. Although therewas no hazing at 145° C., samples warped and the acrylic-modifiedcolloidal silica cracked at that temperature. This system, thoughsuccessful at reducing haze, was not optimized for other performancefeatures.

COMPARATIVE EXAMPLE L

Plaques of polyetherimide (ULTEM 1000) having thicknesses of 3.2millimeters were metallized according with aluminum according to theprocedure of Comparative Examples J and K to create a reflective layerthickness of about 200 nanometers. Samples were tested at oventemperatures of 195 to 210° C. The samples developed haze after timesvarying from 48 hours (at 195° C.) to 3 minutes (at 210° C.).

EXAMPLE 14

A 3.2 millimeter thick plaque of polyetherimide (ULTEM® 1000) was coatedwith a plasma-polymerized organosilicone layer to yield a coatingthickness of about 2 micrometers. The plasma deposition was carried outusing an expanding argon thermal plasma at 70 amps with 1.65 standardliters per minute (slpm) of argon. Deposition was carried out in twocoating passes each about 1 micrometer thick. Oxygen andoctamethylcyclotetrasiloxane (D4) were fed downstream of the expandingplasma through a ring injector. The feed rate of D4 was 0.19 slpm inboth passes, and the feed rate of oxygen was 0.3 and 0.8 slpm in thefirst and second passes, respectively. The sample was then metallized bysputtering aluminum onto the plasma-polymerized organosilicone surfaceto yield a reflective layer thickness of about 200 nanometers. Thesample was oven tested as described above. No hazing was observed attemperatures up to 220° C.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

1. A data storage medium, comprising: a substrate comprising anamorphous thermoplastic resin having a heat distortion temperature of atleast about 140° C. measured at 66 pounds per square inch according toASTM D648. a density less than 1.7 grams per milliliter, and an orannicvolatiles content less than 1,000 parts per million measured accordingto ASTM D4526; a reflective metal layer; a haze-prevention layerinterposed between the substrate and the reflective metal layer, whereinthe haze-prevention layer comprises a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch measured according to ASTM D638 at 25° C.; wherein thehaze-prevention layer has a thickness of 145 nanometers to about 100micrometers; wherein the haze-prevention layer contacts the substrateand the reflective metal layer; and a protective metal oxide layerhaving a percent transmittance of at least 90% measured according toASTM D1003 at 25° C.; wherein the reflective layer is interposed betweenthe haze-prevention layer and the protective metal oxide layer; andwherein the reflective layer contacts the protective metal oxide layer;wherein the haze-prevention layer comprises a plasma-polymerizedorganosilicone, wherein the organosilione has the formula

wherein each occurrence of R is independently C₁-C₆ alkyl, C₂-C₆alkenyl, C₃-C₆ alkenyl alkyl, or C₆-C₁₈ aryl; n is 0 to 100; and m is 1to 100; and wherein the data storage medium is adapted for reading viathe substrate.
 2. The data storage medium of claim 1, wherein theamorphous thermoplastic resin is selected from polyetherimides,polyetherimide sulfones, polysulfones, polyethersulfones, polyphenyleneether sulfones, poly(arylene ether)s, polycarbonates, polyestercarbonates, polyarylates, and mixtures thereof.
 3. The data storagemedium of claim 1, wherein the amorphous thermoplastic resin comprises apolysulfone or an isophorone bisphenol-containing polycarbonate.
 4. Thedata storage medium of claim 1, wherein the substrate is substantiallyfree of inorganic filler.
 5. The data storage medium of claim 1, whereinthe substrate has a thickness of about 0.1 to about 20 millimeters in adimension perpendicular to the haze-prevention layer and the reflectivemetal layer.
 6. The data storage medium of claim 1, wherein thereflective metal layer comprises a metal selected from aluminum, silver,gold, nickel, palladium, platinum, copper, and alloys thereof.
 7. Thedata storage medium of claim 1, wherein the reflective metal layercomprises aluminum.
 8. The data storage medium of claim 1, wherein thereflective metal layer has a thickness of about 10 to about 1000nanometers.
 9. The data storage medium of claim 1, wherein theorganosilicone is octamethyl(cyclotetrasiloxane),hexamethyl(cyclotrisiloxane), tetramethyldisiloxane,hexamethyldisiloxane, octamethyltrisiloxane,cyclotetra(methylvinylsiloxane), cyclotri(methylvinylsiloxane), or amixture thereof.
 10. The data storage medium of claim 1, comprising asurface with a reflectivity of at least 80% measured according to ASTMD523.
 11. The data storage medium of claim 1, wherein the protectivemetal oxide layer comprises an oxide of titanium.
 12. The data storagemedium of claim 1, wherein the protective metal oxide layer comprises anoxide of zinc.
 13. A data storage medium, comprising: a substratecomprising a polysulfone or an isophorone bisphenol-containingpolycarbonate resin having a glass transition temperature of at leastabout 170° C., a density less than 1.7 grams per milliliter, and anorganic volatiles content less than 1,000 parts per million measuredaccording to ASTM D4526; a reflective metal layer comprising aluminum; ahaze-prevention layer interposed between the substrate and thereflective metal layer, wherein the haze-prevention layer comprises aplasma-polymerized organosilicone having a volume resistivity of atleast 1×10⁻² ohm-centimeters measured according to ASTM D257 at 25° C.and a tensile modulus of at least about 5×10⁵ pounds per square inchmeasured according to ASTM D638 at 25° C.; wherein the haze-preventionlayer has a thickness of 145 nanometers to about 100 micrometers;wherein the haze-prevention layer contacts the substrate and thereflective metal layer; and a protective metal oxide layer having apercent transmittance of at least 90% measured according to ASTM D1003at 25° C.; wherein the reflective layer is interposed between thehaze-prevention layer and the protective metal oxide layer; and whereinthe reflective layer contacts the protective metal oxide layer; whereinthe organosilicone has the formula

wherein each occurrence of R is independently C₁-C₆ alkyl, C₂-C₆alkenyl, C₃-C₆ alkenyl alkyl, or C₆-C₁₈ aryl; n is 0 to 100; and m is 1to 100; and wherein the data storage medium is adapted for reading viathe substrate.
 14. A method for preparing a data storage medium,comprising: applying a haze-prevention layer to a surface of asubstrate; wherein the haze-prevention layer comprises a material havinga volume resistivity of at least 1×10⁻⁴ ohm-centimeters measuredaccording to ASTM D257 at 25° C. and a tensile modulus of at least about3×10⁵ pounds per square inch measured according to ASTM D638 at 25° C.;wherein the haze-prevention layer has a thickness of 145 nanometers toabout 100 micrometers; wherein the haze-prevention layer comprises aplasma-pulymerized organosilicone. wherein the organosilicone has theformula

wherein each occurrence of R is independently C₁-C₆ alkyl, C₂-C₆alkenyl, C₃-C₆ alkenyl alkyl, or C₆-C₁₈ aryl; n is 0 to 100; and m is 1to 100; and wherein the substrate comprises an amorphous thermoplasticresin having a heat distortion temperature of at least about 140° C.measured at 66 pounds per square inch according to ASTM D648, a densityless than 1.7 grams per milliliter, and an organic volatiles contentless than 1,000 parts per million measured according to ASTM D4526;applying a reflective metal layer to a surface of the haze-preventionlayer; and applying a protective metal oxide layer to the reflectivemetal layer; wherein the protective metal oxide layer has a percenttransmittance of at least 90% measured according to ASTM D1003; whereinthe data storage medium is adapted for reading via the substrate.